Great baked vegetable casseroles, like this one, feed crowds so well. This one is inspired by two sources: my beloved Armando al Pantheon, which has a fab version, and Elizabeth David, the writer who stoked the British passion for Italian eating. She had a breezy style to her recipes, even if they can be irritatingly vague. So here I’ve tried to be a little more helpful in my instructions, while hoping you s